6i4 



HUMAN ANATOMY. 



I Extens. carp. rad. 



^''^f^ long, et brev". 



'^ — - — P~xt. brevis pollicis 



^ Ext. ossis 



metacarpi pollicis 



Ext. longus 

 pollicis 



" It must be noted that the front of the hand,- and especially the palm, is singu- 

 larly free from surface veins. Indeed, the great bulk of the blood from the hand is 

 returned by the superficial veins on the dorslim of the lingers and hand" (Treves). 



The annular ligaments at the wrist are of importance in their relation to the 

 tendons and their sheaths. The tendon-sheaths (Fig. 591) which pass through the 

 six compartments in or under the posterior ligament behave as follows. i. That 

 for the short extensors and the extensor of the metacarpal bone of the thumb runs 

 from the joint between the first metacarpal and the trapezium to a point almost an 

 inch above the styloid process of the radius. 2. That for the long and short radial 



extensors of the carpus runs 

 Fig. 591. from the insertions of those 



muscles to a point a half inch 

 above the ligament. 3. That 

 for the extensor longus pol- 

 , licis runs from the insertion 



to the upper border of the 

 ligament. 4. That for the 

 extensor indicis extends from 

 the upper border of the met- 

 acarpus, and that for the ex- 

 tensor communis from the 

 middle of the metacarpus, 

 both to the upper border of 

 the ligament. 5. That for 

 the extensor minimi digiti 

 runs from the middle of the 

 metacarpus ; and 6, that for 

 the ulnar extensor of the car- 

 pus from the insertion, both 

 to the upper border of the 

 ligament. 



Infective disease of the 

 dorsum of the wrist and hand 

 is rare as compared with the 

 palmar surface. The dense 

 connective-tissue fibres of the 

 palm run vertically down- 

 ward to the palmar fascia 

 and tendon-sheaths, and thus 

 convey infection directly to 

 the deeper parts. This layer 

 is often described as the su- 

 perficial palmar fascia. The 

 subcutaneous connective-tis- 

 sue fibres on the dorsum run 

 horizontally, and infective in- 

 flammation is therefore more 

 likely to remain superficial 

 (Warren). If, however, it 

 does penetrate and gains 

 the tendon-sheaths, the natural anatomical limitations are those indicated 



Ext. carp, ulnaris. 



Posterior 

 annular ligament 



Ext. min. digiti 



Ext. communis 

 et indicis 



Dissection ot dorsum of hand, showing artificially distended sheaths of 



extensor tendons. 



access to 

 above. 



Teno-synovitis from strain, from gout, or from rheumatism is especially frequent 

 in these sheaths, on account of their exposure to wet and cold, and also because the 

 muscles connected with them are relatively weak and are less often used than those 

 on the palmar surface of the forearm. They are thus more liable to strain from 

 unaccustomed exertion. 



Ganglion of the simple (non-tuberculous) variety is also frequent here, probably 

 for the same reasons. 



